Presently, with the advance of digital photographic technologies, various of electronic devices (such as digital cameras, digital video cameras, notebook computers, and mobile phones and etc.) having digital image-capturing elements are continuously developed and improved. There is a trend to enhance the photographic quality of the electronic devices, minimize the volume thereof, and lower the selling price thereof. Therefore, electronic image-capturing devices are more and more popular in the market. As a result, it is important for related manufacturers of the electronic image-capturing devices to develop and design an electronic image-capturing device having an intelligent image capturing function for satisfying basic photographic functions needed by most users and overcoming the insufficient photographic skill thereof.
Generally, most of various photos captured by a traditional electronic image-capturing device operated by a user are portrait photos. When capturing a portrait photo, the user usually continues to seek for a suitable transient scene, in order to capture a portrait photo, which can show a best appearance of the captured person. However, what kind of the appearance is the best one which can be agreed and accepted by the most users? The answer is an appearance showing a smile face of the captured person during his/her mouth is slightly opened and corners of the mouth are slightly raised. Thus, when capturing a portrait photo, the captured person usually hopes that a photographer can capture a portrait photo when the captured person transiently shows his/her smile face. However, in fact, it is unfortunate that the captured person generally can not have a timely communication or a sufficient consensus with the photographer, such that the captured person can not be precisely aware of the best transience when the photographer presses a shutter button. As a result, when the photographer presses the shutter button, the captured person may unwittingly close his/her mouth, resulting in generating an unnatural or stiff face. Even, after the photographer told the captured person to keep smiling and be ready for taking a photo, the captured person still can not continuously keep the same smile face. As a result, the captured person may close his/her mouth at the transient moment of pressing the shutter button. In other words, the original smile face of the captured person may suddenly become the unnatural or stiff face. The foregoing unexpected conditions cause the portrait photo captured by the photographer only shows the unnatural or unbeautiful face, which may not be satisfied or accepted by the captured person. Especially, when the photographer takes a photo of many people or children, the portrait photo inevitably shows closed mouths of the captured people. Specifically, if the photographer can not take a photo having smile faces of all captured people in a memorable or a rememberable day, it will be very regrettable. As a result, it is important for related manufacturers of electronic image-capturing devices to develop and design an image correction technology for improving the electronic image-capturing devices to be capable of detecting if the mouth of the captured portrait photo is in a closed stiff state and automatically repairing the mouth when the mouth is determining to be closed, so as to automatically repair the mouth to be in a smile state having a slightly opened mouth and slightly raised corners, thereby enhancing the portrait photo more natural and more esthetic, and substantially increasing the successful ratio of taking good portrait photos.
It is therefore tried by the inventor(s) to develop a method for detecting a facial expression and repairing a smile face of a portrait photo to solve the problems existing in the traditional electronic image-capturing device that can not precisely determine if the mouth of the captured person is in an unnatural or stiff state at the transient moment of pressing the shutter button, resulting in only capturing a portrait photo captured by the photographer, which can not be satisfied or accepted by the captured person, as described above.